Forage Insect Update

We have had an interesting year so far in our hay crop. Our dry Spring kept us from truly getting started, and the current rain is keeping growers from cutting. We have hundreds of acres that hasn’t been cut yet. If it has been cut, it’s mostly been cut once. There is a very small amount of hay that has been cut twice.

This may be one reason we are seeing stem maggot in some fields. I stopped by this field Wednesday, and a large section appeared frosted. Stem maggot has done lots of damage here. The good news is we have yet to see fall armyworms. This too may be cause the rain.

UGA Extension Forage Specialist Dr. Dennis Hancock has given an update on some other insect issues throughout the state:

Bermudagrass Stem Maggot

Damage from bermudagrass stem maggot

Reports of the bermudagrass stem maggot have been coming in from all over the Coastal Plain and into the southern 2-3 counties in the Piedmont. I suspect with the abundant rainfall in most places, we will see BSM pressures similar to the heavy pressure we saw in 2013. Producers need to employ the standard suppression technique (labeled pyrethroid of their choice 7-10 days after cutting and again 7-10 days later, as needed). Moderate N fertilization rates, and good K fertilization minimizes disease and this seems to minimize BSM activity (but it doesn’t eliminate it). In the past, we have recommended spinosad, as well. Current research indicates this is not as effective as we believed it to be. Pyrethroids are our best option currently. We have a new Extension bulletin on BSM found at Bermudagrass Stem Maggot Research Update.

Fall Armyworms

Reports of fall armyworm are also starting to come in. Producers need to scout and spray if the threshold is reached. The newest bulletin is Caterpillar Pests in Pastures and Hayfields.

Where BSM activity is high and FAW pressure is imminent, consider using Besiege (Lambda-cyhalothrin for the BSM and active FAW; Chlorantraniliprole for residual control of FAW).

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Timing N, Ca, and Boron On Peanuts

Peanuts are looking really good now. We are between pegging and developing seeds at this time. We are on our second and third fungicide applications across the county. We are starting to see evidence of caterpillars. I saw some three corner alfalfa hoppers yesterday as well.

UGA Extension Fertility Scientist Dr. Glen Harris wrote a good piece of information on timing nutrients in peanuts. (Since I already wrote about applying landplaster, I moved the calcium to the bottom since it is a lot to read.)

Timing is everything right? Well, that’s not exactly true when it comes to applying these fertilizer nutrients on peanuts. Rate, source and placement, to round out the “4Rs” of fertilizer management, are important too. When it comes to timing though, if you are too early or too late you could come up short on providing these key nutrients to peanut.

Nitrogen – If peanuts are inoculated or in a short rotation, they should not need any nitrogen fertilizer. This includes putting nitrogen in a starter fertilizer or spraying foliar nitrogen. However, in the case of an inoculation or nodulation failure, nitrogen fertilizer will be recommended as a “rescue” treatment. The timing for fixing this problem is critical and should be detected and fixed around 30 days after planting or soon thereafter. It only takes 60 lb. N/A to fix the problem. Yes, peanuts normally fix more N than that, but recent research as shown that 60 lb. N/A is enough. Split applications and rates up to 180 lb. N/A yielded no more peanuts than the 60 lb. N/A treatment. Ammonium sulfate also seems to be the product of choice in this situation.

Developing seed (R5 Reproductive Growth Stage)

Boron – Since boron is important for pollination and fruiting, the recommended timing for B applications on peanuts is early bloom. And since it is a micronutrient that foliar feeds well, the recommended practice is to include boron with early fungicide sprays. Can you apply boron to the soil at planting? Yes, but this timing may be considered too early since like nitrogen, boron can be highly mobile in soils, i.e. leach out and not be available later when needed. And how late is too late to apply boron? Again, since peak pod fill for peanuts occurs 60 to 90 days after planting, once peanuts are 80 days old or older, the chances of applying boron and getting a yield increase decrease dramatically. And what about rate? The UGA recommendation for B on peanuts is 0.5 lb. B/A. This can be applied in one application or split into 2, 0.25 lb. B/A applications. Rates higher than 0. 5 lb. B/A in a single application can cause burn to the foliage. Rates less than 0.25 lb. B/A, for example 6 ounces of a 5 % liquid B that only provides 0.025 lb. B/A, are considered ineffective and not economical.

Boron burn on peanuts

Calcium – The two most common ways of supplying calcium to the pegging zone of peanut are lime at planting and gypsum (calcium sulfate) at early bloom. Again, timing of applying these two is critical and is linked to the solubility of calcium in these materials. The calcium in lime is not as soluble as the calcium in gypsum so it must be applied earlier to give it time to get in the pegging zone. Applying lime at early bloom is too late.

What about applying gypsum at planting? I get this question all the time. While in some years you could probably get away with this, in other years, like this year for example, applying gypsum at planting would have been too early and not a good idea. Heavy rains on sandy soils can actually “leach” (dissolve and move downward) the calcium right past the pegging zone (top 4 inches). If you applied gypsum too early or if you got 4 to 6 inches of a “leaching rain” soon after application, then you may consider reapplying the gypsum.

Of course, you may want to take a hard look at if you needed gypsum in the first place by looking at your calcium levels and the calcium to potassium ratio in a soil sample from the pegging zone. And what if you are about 60 days after planting and don’t want to run over lapped vines and discover you need some calcium? The period from 60 to 90 days after planting is considered “peak pod fill” and research has shown that applying 10 gal/A of calcium chloride thru the pivot with irrigation water can provide some much needed calcium to developing pods. This treatment will not raise the soil test calcium levels like lime or gypsum will but can be effective.

And what about foliar feeding calcium? The answer for timing of that one is easy…never! Calcium simply does not translocate form leaves to developing pods plus you could never get enough calcium to the pods from a quart per acre foliar calcium even if it did work.

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Weather Outlook For July And Beyond

We are blessed with rain these past two months. In some cases, we have more than we want. Drought is almost entirely gone from the Southeastern US at this time. Rainfall across some parts of Georgia were abundant, with rainfalls up to 300% of normal. The rainfall and clouds have also kept the temperatures down below normal by blocking out the sun’s energy. Below is an outlook of what we may expect from here on from UGA Extension Climatologist Pam Knox:

The outlook for July and beyond shows that there is a continued chance of above normal rainfall for the next month, although that abates somewhat later in summer. Temperatures are expected to be closer to normal than in previous seasons, although there is not much skill in making summer forecasts, especially when ENSO conditions are neutral (not El Nino or La Nina). The neutral conditions do make it likely that the Atlantic hurricane season will be more active than usual, so some areas could see a lot of rain from any storms that do materialize, but of course we don’t know where those will go, so areas right along the path could see a lot of rain while others outside the path could see none, similar to what happened in 2016 with Hurricanes Hermine and Matthew across the Southeast. Because of the increased chance of rainfall and the cooler temperatures, I expect that irrigation will be less needed than in some previous years, but of course it depends on the growing stage of the peanuts and the type of soil they are in as well. Whatever rain does come is likely to be in hit-or-miss showers which may cause widely variable conditions across short distances.

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Spider Mites In Cotton

With this heat, it gets dry quick. I found a few plants with evidence of spider mites yesterday. This of course is not good since it is early. When we are scouting fields, look for spider mites. Look for the reddening on the “V” part of the leaf. UGA Extension Entomologist Dr. Phillip Roberts says early detection is critical.

**The best management practice is to NOT flare spidermites with unnecessary insect sprays. If our retention is good (plant bugs), stink bug threshold is low, and aphids have crashed, we need to hold back. It’s about to get hotter, and dry weather makes them worse too.

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Cotton Blooming: Insect Update

Some of our earliest planted cotton is now blooming. I thought it would be good to go through an insect update.

Aphids / Beneficial Insects

As reported last week, we found the aphid fungus in Thomas County. UGA Extension Entomologist Dr. Phillip Roberts located the fungus in Tift County last week. Once it’s found in a field, it takes about a week to ‘crash’ the aphids. There are still reports of aphids this week, and I’ve had a question or two. Remember, UGA has not found any yield difference in treating aphids. We’ve had more aphid populations this year, but I would hesitate on treating, especially when they are in ‘hot spots.’ We need to watch beneficials.

In one field this week, I saw many, many lady beetles. On one plant, I saw almost all of its life stages, confirming how many beneficials are in our fields now. The lady beetles can’t eat all these aphids, but the aphids are bringing them to the field. I’ve seen some parasitic wasps too.

Lady beetle puapae

Lady beetle larvae – “Baby alligator”

Plant Bugs

I haven’t talked about plant bugs this year. In fields I go in, retention has been good. 80% retention is our goal. I have seen a plant bug here and there. Dr. Roberts says that in the state, they have been spotty, and only a small acreage has been treated to date.

Sting Bugs

It is now time to scout for stink bugs in blooming fields. Scouts need to crack bolls and look for warts and calloused walls. Treatment decision is based on % of bolls damaged.

Silverleaf Whiteflies

Dr. Roberts says whiteflies are a month early. This is usually an indication of a rough year. We need to look for adults. The precense of adult whiteflies influence deicisions of other pests. Treatment for whiteflies must be timely as well. For more on thresholds and insecticides, visit this previous post on Silverleaf Whitefly Management.

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Citrus Grower’s Summer Update – July 26th

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July 6, 2017 · 10:31 PM

Managing Silverleaf Whiteflies In Cotton

Probably the biggest agriculture pest topic last year, whiteflies became a problem very fast. Because of our warm winter, white are already present, likely meaning another bad year. The goal in silverleaf whitefly (SLWF) management is to initiate control measures just prior to the period of most rapid pest population development. UGA Extension Entomologists Dr. Phillip Roberts and Dr. Mike Toews put together some info on SLWF:

Risk for SLWF

  • Hairy leaf > smooth leaf cotton.
  • Late planted > early planted cotton.
  • Hot and dry > rainy conditions.

Scouting

SLWF adults (solid white wings) and immatures will be found on the underside of leaves. SLWF populations are best estimated from the 5th main stem leaf below the terminal. Main stem leaves are attached directly to the main stem by their petioles. The top or first main stem leaf is defined as the uppermost leaf which is 1 inch or larger in diameter. Adults and nymphs should be counted on the 5th main stem leaf below the terminal.

Adult whitefly in our UGA On-farm Variety Trial on June 29th. Leaves are considered infested when 3 adults are observed. (This counts adults that fly off when leaf is turned over.

SLWF Threshold

Treat when 50 percent of sampled leaves (sample 5th expanded leaf below the terminal) are infested with multiple immatures (≥5 per leaf).

Leaves are considered infested if 5 immatures are observes.

Insecticides

Insect Growth Regulators (Knack and Courier): use of IGRs are the backbone of SLWF management programs in cotton. Effects on SLWF populations are generally slow due to the life stages targeted by IGRs, however these products have long residual activity and perform very well when applied on a timely basis.

Use of other insecticide options which are active on all life stages have quicker effects on SLWF infestations but lack the residual of IGRs.

SLWF is an areawide cross commodity problem. When all parties use sound SLWF management programs all will benefit.

Steps for Efficient Sampling of SLWF

  1. Familiarize yourself with the general location of the 5th main stem leaf in each field.
  2. Select plants at random at least 25 paces into the field and at least 10 paces apart, being careful to keep your shadow from passing over the plant you plan to sample.
  3. Turn the 5th leaf over slowly by its tip or petiole and count the leaf as infested with adults if it has 3 or more adults on it. Include in your counts any adults that fly up from the leaf as you turn it over.
  4. Detach the leaf by the petiole from the main stem. If it fails to snap off easily, you have likely sampled a leaf that is too high on the plant. Recheck your leaf position to make sure you are sampling the 5th leaf.
  5. Examine the bottom of the leaf for the presence of immature SLWFs. Count the leaf as infested if it has 5 or more immatures on the underside of the leaf. Sample at least 30 plants (leaves) per field.
  6. Calculate the percentage of leaves infested with adults and the percentage of leaves infested with immatures.
  7. Treatment is recommended when 50 percent of sampled leaves are infested with immature SLWFs.

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